There are a range of barriers precluding patients from fully engaging in and benefiting from the spectrum of eHealth interventions developed to support patient access to health information, disease self-management efforts, and patient-provider communication. Consumers with low eHealth literacy skills often stand to gain the greatest benefit from the use of eHealth tools. eHealth skills are comprised of reading/writing/numeracy skills, health literacy, computer literacy, information literacy, media literacy, and scientific literacy [1]. We aim to develop an approach to characterize dimensions of complexity and to reveal knowledge and skill-related barriers to eHealth engagement. We use Bloom's Taxonomy to guide development of an eHealth literacy taxonomy that categorizes and describes each type of literacy by complexity level. Illustrative examples demonstrate the utility of the taxonomy in characterizing dimensions of complexity of eHealth skills used and associated with each step in completing an eHealth task.